22 replies to this topic

[Dave Crevie]

I know we don't do this a lot, but there are times when we have to thread a hole or two, particularly in motor cans. Most of us have threaded them free-hand, and sometimes end up threading it crooked, or worse, breaking the tap off in the hole. Here's how to do it properly;

 

https://youtu.be/6UO...DkBmpRiDYpOZPZN

 

You can get this cheap tapper from MSC Direct;

 

Or this better one from Penn Tool;

 

 

 

In a situation where you have a lot of holes to thread, you might want to use an automatic tapping head for a drill press;

 

https://youtu.be/gtY..._QtyeVZqh09kKae

 

 

You can find these used on e-Bay;

 

 

 

Now, if you really have a lot of holes to thread, you can go this route. A  CNC machining center;

 

https://youtu.be/Y3f...r1EAkdeaiGCNsvn

[team burrito]

you can do it by hand, but you have to be smart about it. first - use oil to lube the tap; second - if it tighten up on you, back it out & use more oil; third - take your time.

[dc-65x]

I'm a big fan of tapping gizmos Dave. I like that $250 job but this little Micro Mark one, although not super precise, has worked well for me on my slot cars:

 

[Bill Seitz]

The Micro Mark tapper solves my problem of tapping endbells - the setup has to be held in an angle position which this does nicely. I see a new tool in my future.

[Pappy]

I use these https://www.amazon.c...0cb92f303f6e809 . in my drill press. Spring loaded, keeps the tap straight.

[Dave Crevie]

All good ideas. The Micromark tapper does not come with the v-block, or any holding fixture. The v-block can be purchased from MSC or McMaster-Carr;

 

 

 

The $33 tapper is perfectly fine for what we do.

 

The center finders that Pappy referred to are great for finding the center of the drilled hole, but don't hold taps. You still need to use the chuck, and turn it by hand. Although I became pretty adept at using the on/off switch, I don't recommend that. 

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[dc-65x]

If you don't mind going with a less precise for slot car work import, you can find adjustable angle blocks like I use starting in the $30 range on eBay and Amazon.

[Martin]

I have the same basic setup as Rick has shown, an angle block and a small drill press.

 

A couple of weeks ago Larry and I put our heads together to design and make a dedicated tool where you would slide your motor into a  jig and then be used to pre drill the screw holes perfect every time.

 

It's a simple tool really and at this time it only fits 16d cans as that is what Larry and I are playing with. If there is demand we can make different size Jigs for different motors?

Larry measured the screw holes on a Parma 16D can at 26 degrees. Is there a standard, we noticed Rick, you have your angle block set at 24 degrees? 

We are making prototypes at this time to prove that our concept works as good as we expect.  So stay tuned if interested.                                      

[Dave Crevie]

A drill fixture is the absolute way to go, and can be designed to do both drilling and tapping. You do need to make interchangeable nests to hold the different can sizes. The problem here is that few people on this site have the knowledge or equipment to make that type of fixture. If you had a CNC machining center, you could turn out those fixtures for about $50.00 each. Not including the aluminum material you would be best to use. (maybe another $10.00/unit) 

[Martin]

" A drill fixture is the absolute way to go," That's what we thought Dave.

 

Price is even better than that Dave. Target price is less than $50.  Pilot drill, hardware and shipping included. Plus I will take care of the a 5% commission to our host SLOTBLOG.   

Larry and I will test  prototypes early next week.

If all is good will make a short run of 10-20 units depending on interest. 

[Dave Crevie]

You might want to include the tap, for a couple reasons. To buy a single tap is almost as expensive as the packs of five. You don't want guys using fine thread taps in plastic. They strip out too easily. Not everyone has an account at an industrial supply, so if they buy from a hardware store, they will be paying way too much. 

 

Also, I find using thread forming taps make stronger threads in nylon. Something to consider. Use "Green Stuff" tapping soap for this.

[Martin]

Thanks for your input Dave, your experience is always most welcome.    My plan was to use self tapping button head screws with a .050 allen wrench size. They are low profile, and they really bite well into the nylon endbell.

 

This 16D drill Jig eliminates the need for layout discrepancies and because both can and endbell are drilled in the jig you can replace worn or damaged parts and they will fit Endbell to Can the same every time. 

 

If anybody has other screws that are better in some way, I am open to suggestions at this stage. 

 

Rick any thoughts on the angle question, how did you arrive at 24 degrees ? We have it at 26. We will check that.

[Dave Crevie]

 My plan was to use self tapping button head screws with a .050 allen wrench size. They are low profile, and they really bite well into the nylon endbell.

 

 

 

I always use self-tapping screws in plastic endbells. Self-tappers do get a better "bite" into the plastic. But we might find that the guys building motors are going to use aluminum endbells when they have them. I'm talking pro racers, now. The kind that would invest in a $500.00 tire truer. Other than that, the "restorers" are going to be your biggest market. The ones that care that the endbell screws go in straight. ( the ones restoring old RTRs will probably stick with the fold-over tabs for originality ) 

[team burrito]

I always use self-tapping screws in plastic endbells. Self-tappers do get a better "bite" into the plastic. But we might find that the guys building motors are going to use aluminum endbells when they have them. I'm talking pro racers, now. The kind that would invest in a $500.00 tire truer. Other than that, the "restorers" are going to be your biggest market. The ones that care that the endbell screws go in straight. ( the ones restoring old RTRs will probably stick with the fold-over tabs for originality ) 

whatever you do, don't use those awful pin tabs! those are the worst fasteners ever!
 

[Dave Crevie]

Which is why we went to screws to hold the endbell in place. But if you are restoring to 100% original, you have no choice but to use the tabs.

[team burrito]

Which is why we went to screws to hold the endbell in place. But if you are restoring to 100% original, you have no choice but to use the tabs.

i would make an exception in this case.
 

[Dave Crevie]

I really only mentioned it because that is the direction my slot racing has taken. Hopefully I can get back to building and continue to restore some of the cars I built, bought or was given during my early involvement in slot racing. ( I never throw anything away )  I have an affinity for old things; cars, trains, planes and boats. Back in the '80s I helped restore a GarWood crackerbox with an Allison aircraft engine in it. I went along on their first test when the project was finished, on the Fox River west of where I live. Spent four hours in the West Chicago, Il., jail for a bagfull of infractions we committed  while doing that. 

[Martin]

I had to look that up Dave, always loved the old wooden boats. 

[Dave Crevie]

I searched the net. Couldn't find a picture of the boat. It was a well known boat that raced just before WWII, and again after the war was over. But by the 1950s hydroplanes were coming of age, and they became the darlings of the upper crusty boating set.  

[Martin]

I did find this small pic but it would not let me post until I took a screenshot.

 

[Dave Crevie]

That is the same basic design. That model was called the Speedster. The one I worked on was ten feet longer, and had an angle to the transom leading down towards the water line. On a smooth lake, we clocked it at 87 mph, which would have been a record for the class back in 1939. A short video of crackerbox racing in 1938;

 

https://youtu.be/NlZ3DCAN49A?si=_VRT2Pa02Lp9IEtG  

 

When Ernie Casale designed and built a v-drive that could handle the big horsepower of the race boats, designers started going to rear-motored boat designs. You see one in this video.

[Dave Crevie]

If you have a CNC machining center, this is how you make threaded holes;

 

https://youtu.be/Nq8...deKPJCXPP3x39MK

 

Oh, I so miss having one of these machines at my disposal. So many projects, so little time.

[Samiam]

This is the answer for me .....

 

http://slotblog.net/...th-broken-tabs/